Safety control apparatus



July 9, 1935. F. D. AUSTIN 2,007,702

SAFETY CONTROL APPARATUS Filed Jan. 19, 1934 Patented July 9, 1935 UNITED STATES PATENT OFFICE 2,007,702 SAFETY CONTROL APPARATUS Frederick 1). Austin, Port Chester, N. Y. Application Januarylll, 1934, Serial'No. 707,411' I 17 Claims. (01. 200-142) This invention relates to improvements in the ditions when it fuses, and the abnormal current general type of safety devices of my United States load must be indicated by other apparatus form- Letters Patent No. 1,910,944, and No. 1,910,945, ing no part of the present safety control device. both dated May 23,1933, and of my co-pending So far as the present invention is concerned,

5 applications, one Serial No.'630,742, and the other the same identical parts as shown in my said 5 Serial No. 630,743, both filed August 27,- 1932. patents and co-pending applications may be Subject matter of invention disclosed but not utilized for illustrative disclosure, or the invention herein claimed is claimed in one or the other of may be applied to various other combinations said oo-pending applications. a where a circuit is governed according to thermic The primary object in view is improvement of conditions. 10

the dependability and eillcacy of the safety device In the accompanying drawing,- to function accurately and to avoid accidental or Figure 1 is a Sectional e evation of astructure undesired operation. embodying the features of the present invention.

A more-detailed object is the protection of a Fi re is p p vev w f he f se uni t-hermicaliy-responsive fuse controlling an elec-' and contiguous'parts segregated and a fragment 15 tric .circuitfrom injurious influence of the electric only of th a y ar for aid pa ts in current. shown.

Another object is to afford such. protection of Fi ure 3 is a l it d n v ti al secti n sncha fuse where the fuseis not normally responu h a p o t slccvc applied t0 the Parts shieto current overload. of Figure 2, parts being seen in elevation, and 20 IA still'further object is the protection of such the parts bei g in the pos t after disrupficn c a thermicallyrresponsive iuse against disintegrathe fuse. tion or disruption whether occurring slowly or Figure 4 is a vertical cross section taken on the suddenly under the action of an electric current, p a e in a d y e of Figure In greater detail, .a further object is thereten- As illustratively app d in e co panying 25 tion of a circuit breaker'against circuit breaking drawing, the parts a e Su a y tical action by a'heat-responsive fuse. with those shown in-Figures 1 and 2 of the draw- An important object achieved by the present ing of y ccpending pp at o Se ial No. invention is the capacity of the improvements t 630,742, above mentioned, but with the present be utilized in units already in use without strucimpr vements incorporated. 3o tural modifications of such units, Referring to the drawing by numerals, I indi- Other objects will become apparent and obviou cates a standard electric 'fitting consisting of afrom the drawing and the description hereinpronged insulating car i r h v n a right an le after given. armor shield 2 to receive anyof the well known 35. In the various safety devices of the abovearmored electriccables with multiple wires. The

mentioned patents and pending applications p o Of the fitting l'al'c Tcliiova'bly ed there is used afuse which is not ordinarily rein an'insulating handle3, which is provided'with sponsive to normal current load, or to a reasonthe customary so e receiving the prongs able degree of current overload, but, since the from the p I d directing th m into contact 40. fuse in such devices is in the circuit, it is subwith the outer terminals of electrical conductors 40 iected to the action of current stresses, and, in 4.4. The conductors 4 extend throughout the some instances through current overload, as from length of .an insulating bar or rod 5'which extends a highstarting torque of the controlled motor, or from the end of and is preferably formed integral from other causes (such as a short circuit) may with the handle 3, the outerend of the rod adbeinjured and thus caused to disrupt undesirably J'acentthe handle being provided with threads 45 and not incident to thermic conditions; and the (shown in my last-mentioned copendingapplicapresent invention contemplates providing all the tion) for being detachably threaded into a meadvantages of, theseveral control devices of the allicshc l 0r ca The Shell at its outer said patents and pending'applications while preend is preferably provided with a. nut-like or poly- 0 serving the thermic fuse-entirely independent of sided handle 8 adapted to receive a wrench or current'action, so that-current overload or other other tool for rotating the shell into operative deleterious .efiect on the thermic fuse is. obviated. position. The shell is provided'with threads 9 ad- In other words, the thermic-responsive fuse is by jacent the handle 8, which threads are preferthe present-invention limited toits functionof ably of the pipe thread type so as to be properly 5 indicating the presenceof abnormal thermic conreceived in any-appropriate pipe coupling or fitting. The shell 1 is preferably, as seen in Figure 1, imperforate and closed at its inner end so as to prevent moisture from reaching the contained parts when the shell 1 is surrounded by moisture. The outer end portion of the shell is internally threaded to receive the thread of the bar 5. The conductors 4 are preferably in the form of rods of resilient material so as to be capable of being sprung toward each other and to normally spring apart as seen in Figure 3. The bar is provided with passageways for the rods 4 after the manner shown in my last-mentioned co-pending application, which passageways preferably are.

widened to produce a single slot II] at the inner or free end of the bar so as to enable and provide for ample spring action of the rods 4.

The free terminals of the rod 4 are preferably flattened or otherwise rendered polysided, as plainly seen at l I, I l, in Figure 2, and are held in a state 'of tension by a heat-responsive fuse unit which maybe of theform shown in any of. my

above identified patents and co-pending-applica tions, or otherwise as found preferable so long as capable of retaining the bars 4 against springing apart until the fuse is disrupted by a dangerously high temperature. An excellent illustrative instanceof an appropriate form of such fuse is the type seen in Figure 2 of the drawings of my co-pending application Serial No. 630,742, which fuse is shown in the accompanying drawing. This fuse is made upof plates l2, I2, and an interposed film of fusing material. Each ofthe plates ,I2is'provided with a sleeve l4 to receive the respective terminals of rods 4 and the sleeves are shaped to snugly receive the'fiattened terminals ,ll and'thusprevent the plates, l2 from rocking or pivoting on the rods 4 when the fuse gives way and allows the parts to move apart under the expanding tension of the rods 4 to the position seen in Figures 3 and 4. r I

The plates I2 are preferably made ofrelatively.

thin sheet metal, such as copper, and the fusing material. is preferably'as thin as is practicable for resisting fusing under heat up to the degree previously determined, and, to that end, the film of fusing material is preferably in the-nature of solder applied as a thin solder coat between thetwo sheets I2, as fully set forth in my last-.

tion therebetweernand the sleeves I 4 may well' be made of insulating material. so that no current whatever *can1pass' between the rods 4 through the "fuse. This, however, is a matter of preference, since, as will become obvious, the

provision of the present improvements obviates thepassage of current through the fuse even though metal be used for making up the sleeves,

l4 and plates l2.

closed during operation, any of various arrangementsmay be employed whereby electric contact is established and retained between the rods 4, so long as th'e'fuse is not disrupted; Any appropriate projection from: one rod towardthe other proportioned and located'to cause electric I contact between; the rods, when the: rods are:

of thefuse. Since-contact'mus't be provided between the rods 4 in order that the circuit maybe retained drawn suii'iciently closely together to receive the sleeves l4, will suffice providing an adequate breaking of contact is assured when the bars 4 spring apart, as seen in Figure 3, on the disruption of the fuse. But I preferably provide for as perfect electric contact as possible between the two rods 4 and as complete and quick disruption of such contact as reasonably practicable to prevent arcing when separation of the rods occurs. To this end, an illustrative and at present preferred embodiment includes the'parts as seen in the accompanying drawing wherein a unit or member similar in general contour and appearance to the fusing unit, except for the l3 will be in face contact and will afford electrical contact, between the rods. The plates l3 and. sleeves l4 with their connecting parts are all of electric conducting material, and the plates l3 are preferably of spring material and are suificiently resilient to spring from the flattened condition seen in Figure 2 to the slanting positions seen in Figure 4 when the plates are re-' leased to separate. The plates are also preferably plated or coated with non-corrosive mate-.

rial, such'as chromium, or made of non-corrosive material, to resist wear and injury. By providing for the slight springing action thus seen, when the plates are in the position seen in Figure 4 and are brought together to the position seen in Figure 2, the edgewise sliding action of each plate on the plate with which it contacts, which must occur as the plates move together, assures a cleanandeffective electrical contact;

Numerous other specific embodiments of the contact producing member or members between the rods 4 will readily suggest themselves, and

may be substituted while providing the results:

and applying the principles of the present invention.

The operation will readily'understood from the foregoing, and consistsessentially in applying a fuse unit to the projecting end portions of the bars 4 after the .contactunit is in' place. Naturally, a reverse orderof these units is possible, but that stated is preferred, where the sleeves 14 are not of insulating material, 'so as to cause the contact unit to be nearer the source" of current and thereby offer a path-of low -resistance relieving the fuse from possibility of def terioration under current stresses. Of course,

where the sleeves I 4 are of insulating matrial, the relative location is not important, except forconvenience of applying a new-fuse unit'after disruption of one in use. 7 It is also important that a sufficient and clean cut spacing of'the plates I3 must occur immediately on disruption By the provision of the present'invention the function of. the safety control fuse for guard= ing againstdangerous thermic conditions it not only assured, but freed'from-confusion withpossible current action. A separate fuse unit'm'ust' be taken care of, and, therefore, the operatoriwill' not exoect of the'present fuse unitany safety against overload or other current conditions that are mmdesirable, except that all current will be cutoff andqaeration stormed whenever a dangerously high temperature isthreatened.

in the practicing of the inventions ofmy several above-ide'ntified patents and applications where surrounding, insulating sleeves have been employed to safeguard-against short circuiting incident to either the presence "of accumulation of fused material or other conditions, the sleeves have been found to behighly satisfactory and effective for the. purpose, except that in some instances a-sleeve has been too loose to retain itself inposition on the insulating bar 5,'and in a few instances theloss of the sleeve has resulted in defective-operatiomso that it has become desirable to guardagalnst such loss. To this end, the bar 5'v is preferably formed with an annular groove 45 at the place of the normal location of the outer end of the protecting sleeve IS. The bar iisformedofhard rubber, or other appropriate insulating material, and the sleeve I6 is formed of similar material and has each of its ends turned inward to provide an annular constriction or'flange H proportioned to seat snugly in the annulargroove l5 when the sleeve is slid onto the bar 5 to the, position indicated in Figure 3. There is a slight-springing action andlexpansion'of the sleeve in being moved to and from this .position, and the resiliency is suflicient toeffect-ively lock the sleeve l6 against accidental detachment from the bar 5 when the parts are-in the position seen in Figure 3. Since a flange I1 is present at each end of the sleeve, and the sleeve is otherwise, a hollow cylinder, either "end may be'applied to the bar 5 when the parts are being assembled. The resistance to the necessary expansion of the sleeve to allow the same to slide into or away from the position seen in Figure 3 is not sufficient to render such movement diflicult, but is sufficient to insure retention of the sleeve during use and when the bar 5 is being handled outside of shell 1.

While the invention is shown applied in use in one of my preferred embodiments known as an adapter, it is obviously applicable wherever it is desirable to control the operation of a furnace or other heat source, and to stop such operation on reaching a dangerously high temperature. The lead wires (not shown) which extend into the part 2 are, of course, connected to the controlling motor or other controlling parts to supply current thereto, so that, when the circuit is broken, as indicated in Figure 3, there is a cessation of opportunity for increase in temperature. The operator must renew the fuse before the apparatus governed by the current passing through the conductors or rods 4 will operate again. This renewal is preferably accomplished by first withdrawing the sleeve l6 longitudinally, and then longitudinally withdrawing the plates l2 with their sleeves l4, drawing the rods 4 toward each other until the plates l3 are moved from the position seen in Figure 4 to the position seen in Figure 2, and then sliding a fuse unit onto the rods 4 to the position seen in Figure 2 so that the contact between the rods 4 established by the plates l3 will be maintained.

While it is obvious from the drawing of this application, as well as from the disclosure of the above-mentioned patents and applications, that the present invention is well adapted for controlling the current to the fuel supply motor or for otherwise controlling the combustion of a furnace incident to'the water level thereof, it should also be apparent that other parts may be similarly controlled and that the temperature change governing the responsiveness of the fuse may be caused to be felt by the unit otherwise than through the drop of the liquid level.

The sleeve 16 is of hard rubber, gutta percha, or fiber or other appropriate insulating material, and the flanges I! may be formed thereon in any desired manner, as by turning or spinning the terminal edges of the sleeve over to the flanged condition after the sleeve has been otherwise completed.

Since the inner extremity of the shell I is located in the least cooled area. of the adapter, I have found that at times, if the sleeve l6 be imperforate and open only at its ends, the heat developing within the sleeve occasions a substantial pressure and sometimes the fuse of the fusing unit I2 is disrupted prematurely owing to such pressure and heat. To 'insure better circulation of air and thus relieve the pressure, and also to allow distribution of heat more nearly directly from the area surrounded by the sleeve [8, I provide vents or apertures l8, l8, located about the sleeve and in the length of the sleeve at sufliciently frequent intervals to enable the cooling effect of the water which surrounds the shell I to be sufficiently felt within the area surrounded by sleeve Hi to avoid premature disruption of the fuse.

What is claimed is:

1. In safety control devices, the combination, with electrical conductors movable relatively to each other, of a thermically-responsive fuse physically and electrically connecting the conductors to retain them against relative movement, and means additional to the fuse electrically connecting said conductors while the conductors are thus held by said fuse.

2. The combination as claimed in claim 1 wherein the additional means electrically connecting said conductors is independent of the fuse.

3. The combination as claimed in claim 1 wherein the additional means electrically connecting said conductors is independent of and spaced from the fuse.

4. The combination as claimed in claim 1 wherein the additional means electrically connecting said conductors is independent of and spaced from the fuse in the direction toward the source of current.

5. The combination as claimed in claim 1 wherein the additional means for electrically connecting said conductors comprises separable parts adapted to be separated and thus to break electrical contact between the conductors when the conductors are moved.

6. The combination as claimed in claim 1 wherein the conductors are tensioned under resilient stress tending to move the same to contact breaking position when not held by the fuse.

'7. The combination as claimed in claim 1 wherein the conductors are tensioned under resilient stress tending to separate the conductors to a circuit breaking position when the conductors are not held by the fuse.

8. The combination as claimed in claim 1 wherein the means electrically connecting said conductors comprises plates in face contact with each other and carried by the respective conductors.

9. The combination as claimed in claim 1 wherein the means electrically connecting said conductors comprises plates in face contact with each other and carried by the respectiveiconductors, the plates being te'nsionedunder re-i conductors comprises plates in face contact with each other and movable apart, and a sleeve for each of the plates, one of the sleeves surrounding one of the conductors and the other sleeve sur-' rounding the other conductor, each of the coni ductors having a' flattened portion and each of the sleeves having a flattened portion engagingthe flattened portion of the respective conductor and thus preventing angular movement of the respective plate with regard to its conductor.

12. In safety control devices, the combination, with a pair of resilient conductors tensioned to spring apart when released and a fuse physically and electrically connecting and restraining said conductors against separation, of metal plates electrically connected to said conductors inde-' pendent of the fuse and in face contact while the conductors are thus held by the fuse, the said plates being proportioned to be separated from electrical contact under the movement of the conductors when released by the fuse.

13. The combination, with conductors adapted to be disposed in an electrical circuit, of a thermically-responsive fuse physically and electrically connectingand retaining the conductors against relative 'movement under normal temperatureconditions andwhile'thefuse is'preserved against disruptionfrom high temperature, and means closing the circuit between said conductors while the conductors are thus/retained, said means being proportioned and adapted'to cause the cir-:

cuit'to bebroke'nrbetween the conductors when the conductors move on' being released by the fuse incident to disruption of the fuse.

14. The combination, with'm'ovable conductors and a control fuse therefor retaining the conductors inoperative relation, of an insulating bar carrying said conductors, an insulating sleeve surrounding said-v fuse and detachably surrounding a portion of'said' bar, there being between the sleeve and bar a frictional connection comprising a projection extending fromone and a recess in the other receiving said projection, whereby the sleeve mustiexpand in moving to and from a seated position on the-bar. I 7

l5. The'comb'ination as claimed in claim 14 wherein the recess is an annular groove in the bar andthe projection is an inwardly-extending terminal flange on thesleev'e.

16. The combination, with conductors and a control fuse 'therefor; of an insulating bar carrying said. conductors; andan insulating sleeve surrounding said fuse and detachably engaging said bar, the sleeve being laterally vented.

17. The combination as claimed in claim 16 wherein the sleeve has i'ts'end open opposite that engaging the bar. I

' g v FREDERICK D. AUSTIN. 

